Question:

Why are some fields blank when exported to a CSV? The user can see them in the UI.

Answer:

This behavior is caused by the Atomic Security Fields.  If a field is set to Hidden in the Atomic Security Fields on a certain state, the field is blank when exported in that state.  The only way to export this data is for a Vault Owner to export the records or the field needs to be changed to Read-Only.

Related Documentation:

Vault Help Documentation: N/A